For years, mine roof trusses have been used as a supplement to roof bolting in mining operations throughout the world, as illustrated and described in my previously granted U.S. Pat. Nos. 3,427,811, 3,505,824 and 3,509,726.
More recently, in order to reduce the time required for installing the roof trusses, a bolting machine employed for installation of the angular roof bolts installs the two opposed bolts of the truss, then quickly moves to another position to install another pair of bolts for the next truss. Workmen later install the horizontal truss member which must be connected to the roof bolts to complete the truss. This should be done as soon as possible in order to complete the truss structure promptly, since it is only after the horizontal truss member is installed and tensioned, that the full support of the truss is effective.
Up to the present time, the installation of the mine roof truss has been prolonged due to the time involved in installing the horizontal truss member, which conventionally must be joined by threaded connections, "U" bolts and other cumbersome means which is time consuming to install. Therefore, despite the fact that the roof bolting machines are capable of installing the angular bolts at a rapid rate, installation of the complete mine roof truss is slow because of the time required to connect the horizontal truss member to the roof bolts.